Correlation system



May 5, 1959 w. D. FULLER CORRELATION SYSTEM C5 Sheets-Sheet l Filed July 20. 1953 MEE.

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INVENTOR. WILLIAM D. FULLER J 61. 90M QZ.

AGENT 3 She'ets-Sheelt INVENTOR. WILLIAM D. FULLER AGENT W."-D.KFULLER CORRELATION SYSTEM JQ@ A9, anla/ML 9,.

May 5, A1959 Filed July 20. 1955 FIGS May 5, 1959 w. D. FULLER coRRELATroN SYSTEM Filed July 20. 1953 3 Shets-Sheet 5 IIS INVENTOR. WILLIAM D, FULLER J A9. @hwg AGENT ;William D. Fuller, Garland,

2,885,590 CORRELATION SYSTEM Laboratories, Inc., Garland, Tex., a corporation of f Delaware Application July 20, 1953, Serial No. 369,027

1 Claim. (Cl. 315-1) This invention relates generally to electronic circuits yThe primary object of this invention is to provide an electronic circuit which functions to deliver an output only when two identical pulses are correlated within the w Another object is to provide a circuit which may be Awhich have a predetermined separation time.

Other objects and advantages of the invention will become apparent from the following description, and for Tex., assignor to Engineering and more specifically to a circuit which depends upon the reception of specific signals for its operation.

the purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawings in which:

Fig. 1 represents a block diagram of the novel correlation system using a correlator circuit of this invention.

Fig. 2 represents a circuit diagram of the amplifier section of this system including the correlator circuit itself.

Fig. 3 represents a circuit diagram of a typical delay .section of the correlator system.

" Fig. 4 represents voltage time graphs of the signal taken .at various points Within the correlator system.

' Fig. 5 represents a simplified embodiment of one por- I" tion of this invention which is useful in explaining the basic theory of operation of the complete invention.

Referring now more particularly to the characters of be observed broadly. An incoming signal T divides at point 11 and an equal voltage signal T1 and T2 goes into each branch of the parallel circuit including correlator 12 and delay network 13 respectively. The signal T1 going into the top correlator branch of the circuit is not sutlicient of itself to produce an output to satisfactorily operate an electrical apparatus which, in this instance, is shown to be a cathode ray tube 14 to which this circuit is shown connected for purposes of illustration. Signal T1 is composed of multiple pulses P1 and P2 having a separation rate of D seconds. The signal T2 passing through the lower branch is composed of pulses P3 and P4. Graphs showing amplitude versus time are shown in Fig. 4 and may be used to illustrate the general function of this device. After signal T1 has passed through amplitier 15 it arrives at correlator 12 in wave form shown at Fig. 4-(a). However signal T2 has been delayed by a time increment exactly equal to the separation rate D, so that after passing through delay network 13 and amplitier 16 it arrives at the correlator 12 in the wave form shown at Fig. 4-(b). In correlator 12 wave forms (a) and (b) are combined in such a Way that the output signal T3 which is delivered to amplifier 17 and cathode ray tube 14 has a Wave form shown at Fig. 4-(c) and n-l reference of this invention, in block diagram Fig. l, the

operation ,of the correlator system of this invention may A '2,885,590 Patented May 5, 959

cludes a pair of negligible pulses P5 and P7 surrounding a pulse P6 of relatively large amplitude.

The correlator-amplierunit circuit 29 as shown in Fig. 2 includes tubes 30 and 31 connected through a circuit including rectifying diodes 32, 33, and a high resist ance 34. The direct input signal T1 to the correlatoramplifier unit 29 comes in at pin 8 of socket 35 and by way of lead 36 to grid 37 of tube 30, while the delayed input T2 from delay network 13 comes into the circuit Vby way of pin 5, lead 38, and grid 39 of tube 31. Delayed signal T2 is amplified at one triode section of tube 31 and by Way of plate 40, lead 41, capacitor 42 and grid 43, is further amplified in the second section of tube 31. The output of the second section is taken from cathode 44, lead 45, and passes through diode 33 to a junction identified as 46. Since the time that delayed signal T2 was in network 13 is equal to the separation rate of successive pulses P1 andP2, pulse P2 of signal T2 appears at junction 46 'at the same instant that a second pulse P2 of initial signal T1 has passed through tube 30 and from cathode 60, lead 61, and diode 32 and also reached junction 46, whereat signals T1 and T2 combine to form T2 and are fed through capacitor 64 to grid 65 of tube 66. The output of one section of this final stage amplifier -tube 66 is taken from plate 67 and through lead 68 is delivered to pin 4 of socket 35, wherefrom it may be delivered to an electrically operated apparatus such as cathode ray tube 14.

The output from plate 67 is also amplified in the second section of tube 66 and is introduced to grid 72 through lead 73 and capacitor 74. The output of this section is taken from cathode 76 and through lead 77 is delivered to pin 6 of socket 35, from which the output may be used to operate any auxiliary electrical apparatus such as a head set (not shown).

-The B+ power supply for all plates of tubes 30, 31, and 66 is taken from pin 3 of socket 35, and the filament supply is taken from pins 2 and 7.

The delay network 13 may be examined in greater detail by reference to Fig. 3. Socket 80 receives signal T2 byway `of pin 4 and delivers this signal to the input inductor 81 by way of lead 82. The delay circuit is composed of a multiplicity of equal inductors 83 in series, and a multiplicity of capacitors 84 connected in parallel. The output inductor 85 connects to pin 8 of socket 80 by way of lead 86. A common ground lead 87 attaches to y pin 1 of socket 80 from whence it is externally grounded.

The sum vof .the individual time delays that signal T2 experiences in each inductor-capacitor section of this circuit add up to the total delay D which equals the separation rate of pulses P1 and P2.

By reference to Fig. 5 the basic theory of operation of this invention may be observed. In this simplified embodiment the pulses P8 and P9 are delivered by pulse generators and 101. The internal resistances of these generators is indicated at Rgl and Rg2. Pulse generator 100 is connected to a load resistor R2 through a shunted diode 103. The second pulse generator 101 is connected to the common load resistor R2 through a second shunted diode 104. Shunt resistors Rbl and Rb2 are of a much larger magnitude than the internal resistance indicated at Rfl and Rf2 as they represent the shunting resistance of their respective diode tubes 103 and 104. Internal resistances Rfl and Rf2 are operative only in the forward direction that the diodes normally conduct current, since the resistance in the opposite direction in this case would be infinite. The relative values of the resistances in this circuit are such that load resistor R1 is equal to or greater than shunt resistors Rbl, Rb2 and is much greater than the sum of internal resistance as in one case and the internal resistance Rgl of the' corresponding generator; the latter resistances Rfl and Rgl being `of the same order of magnitude.

The operation of 'this correlation system when only one generator 100Y emits a pulse P8 which causes a current ow along path 113? to junction point 114 may be examined by reference to Fig. 5. In this path the current encounters resistance Rgl and since resistance Rfl will not pass current in this direction to junction point 114, the path to this point is through shunt resistor Rbl. Upon reaching junction point 114 the bulk of the current will take the path of lower resistance which in this case will be through internal forward resistanceRfZ and'resistance RgZ. A very small current'would divide at point 114 and create a small voltage drop across R1, which would be equal to the voltage drop due to the larger current passing through the small `resistancesRf2 and RgZ, and this 1R drop represents the output voltage at terminals 115, 116.

The operation of this'circuit when both generators 100 and 101 are emitting simultaneous pulses P8 and P9, will be that current ilows along paths 113 and 117 to junction point 114 and the currents at this point lare additive so thatwith the proper ratio of resistancesthe to'tal voltage available at terminals 11S, 116 will approx-imately equal the voltage output of either generator.

The relationship between the output voltage to av single 'pulse voltage when the resistance values are -properly 'selected may be shown by assigninggcertain arbitrary values to`electrical elements'of the circuit. ForeXample `if Rgand Rf relative to'both paths are equalito ..5` oh'm and Rb is 1000 ohms, the output voltage may -be `determined -by Ohms `and Kirchhois rlaws to beon the order of 3;1000 of the initial pulse voltage, which is for the `pur- `poses of operating external electrical apparatus of Va negligible or unusable value. AIf R1 is much `larger than the other values, say `on vthe order of 100,000 ohms it may be neglected in the above calculations.

With the above mentioned values, the output'voltage when the generators are emitting simultaneous Vpulses may be shown to be approximately 99% of the initialrpulse voltage.

An additional advantage is obtained when this system is employed with a cathode ray tube which has Va long persistance phosphorescent face surface. If'signals T `appear in repeated pulse groups having a repetition time on the order of fractions of a second and the persistence time of the tube fact is `several seconds, a plurality of received signals will be additive on the tube face so that increased brilliancy of a` time duration suicient for visual inspection will occur when pulses of lthe correct signal are displayed, but random pulses will be further minifrnized in their visual display.

From the foregoing description it will be readily seen `that there has y.been produced aA device as` substantially fullls the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of this invention, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention as defined in the appended claim.

Having thus described the invention, what is claimed as new and useful and is desired to be secured by Letters Patent is:

An electrical correlation system for connecting a` signal source of multiple spaced pulses having a predetermined separation rate to a cathode "ray tube, comprising: a cathode ray tube, a long persistence phosphorescent face surface on said tube, a correlator-ampliiier unit, a direct path from said source to said unit, a delay path from said source to said unit in parallel with said direct path, 'delay means in said delay path operative to delay* that `portion of `said spaced pulse which enters said delay path by an integral multiple of said separation time, and means to combine said direct and `delay path pulses to` produce -aI` resultant pulse of sufficient power level to momentarily `illuminate the said tube facewhile minimizing thepower level of pulses having a different separation timeysaid lastnamed means comprising a correlator-amplier unit lincluding aldirect path ampliiier tubehaving `an` output cathode, a delay path amplifier tube `having an `output cathode, leads connecting each output cathodel `to 4a common-junction point, a high resistancenconnectingsaid junction 'point to ground,` rectifying 'metallic diodes"'in each lead to said junction point, a` final Stage amplier tube, a leadv from said junction point to saidnfinal stage 'amplifier'tubm a capacitor in said last named leadfand `an^o`utput ylead from said nal stage'amplifertoisaid cathoderay tube.

References Cited in the le of this patent UNITED STATES PATENTS '2,211,942 White Aug. 20, 1,940 l2,266,401 Reeves Dec. 16, 1941 2,358,448 Earp Sept. 19, 17944 l2,412,994- Lehmann Dec. 24,1946 2,535,303 Lewis DCC. 26, 1950 :2,549,780 Earp Aug. 24, 1951 2,557,729 Eckert a June 19, 1951 2,568,265 Alvarez Sept,' 18, 1951 2,580,148 Wirkler Dec. 25, 19,51 V2,643,819 Lee et al June`30,` 1953 2,657,318 'Rack Oct. f27, 1953 2,718,638 DeRosa et al. Sept.` 20, "1955 

